JP2007311973A - Image reader and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To allow reading in high quality by detecting foreign matter such as dust sticking on an optical component in an optical path even in constitution wherein one optical system serves for both illumination light and read light. <P>SOLUTION: A reference plate 43 for flare detection which has its reverse surface painted in black is disposed outside a contact glass 1 where a document is placed, and when flare detecting operation starts, a first scanning body is moved to the position where the reverse surface of the reference plate 43 for flare detection is read, so that a linear imaging element 10 reads its surface image. When neither a deflecting mirror 6 nor return mirrors 8a and 8b have dust thereupon, the read image is entirely black and then it is judged that there is no foreign matter. If foreign matter such as dust is present on the deflecting mirror 6 or the return mirror 8a or 8b, gray or white data is read in the read image by the linear imaging element 10 and its data value is compared with a previously set value to judge that there is the foreign matter when the data is whiter than the threshold value. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image reading apparatus that includes a light source, a lens, a deflecting mirror, an image sensor, and the like, and optically reads image information of an object to be read, and an image forming apparatus equipped with the image reading apparatus.

  FIG. 8 is a perspective view showing a schematic configuration of the entire conventional image reading apparatus, and FIG. 9 is a front view showing a main part of the conventional image reading apparatus.

  8 and 9, the document D is placed on the contact glass 1, and the light from the lamp 2 that is a light source and the light from the reflector 3 that has received the light from the lamp 2 pass through the imaging region 4 of the document D. Irradiated and reflected light from the document D is deflected by the deflecting mirror 6 in the first traveling body 5 and the folding mirror 8a and the folding mirror 8b disposed opposite to each other in the second traveling body 7, and the imaging lens 9 As a result, the light is condensed on the one-dimensional image pickup device 10 and the original image of the image pickup region 4 is acquired one-dimensionally by the one-dimensional image pickup device 10.

  The driving force of the motor 11 is transmitted to the first traveling body 5 and the second traveling body 7 via the transmission means 12, and the first traveling body 5 travels at twice the speed of the second traveling body 7. As a result, the contact glass 1 travels in a direction perpendicular to the line-shaped imaging region 4 while maintaining the imaging position of the imaging lens 9 on the light receiving surface of the one-dimensional imaging device 10. The images of the original D are sequentially read out by the one-dimensional image sensor 10 and acquired in two dimensions. The direction in which the first traveling body 10 travels is the sub-scanning direction, and the image reading direction of the one-dimensional image sensor 10 is the main scanning direction.

  Usually, a one-dimensional CCD (charge coupled device) is used as the one-dimensional image sensor 10, and the imaging lens 9 reduces the original image on the contact glass 1 and forms an image on the one-dimensional image sensor 10. . Further, since the traveling speed ratio between the first traveling body 5 and the second traveling body 7 is set to 2: 1, the traveling distance of the second traveling body 7 is half of the moving distance of the first traveling body 5, The distances from the imaging region 4 to the imaging lens 9 and the one-dimensional imaging element 10 are constant regardless of the positions of the first traveling body 5 and the second traveling body 7.

In the image reading apparatuses as shown in FIGS. 8 and 9, it has been recently demanded to perform high-speed reading. To cope with this, the weight of the traveling body is reduced and the motor driving load is reduced. Can be considered. In Patent Document 1, a light source is arranged on the upper and lower sides of an image sensor fixed in the apparatus main body, and a reading position is illuminated using a deflection mirror while sharing an imaging optical system of the image sensor. An image reading apparatus is described.
JP-A-10-190990

  However, in the configuration of the image reading apparatus described in Patent Document 1, the optical system of the illumination light that illuminates the original and the optical system of the read light that is reflected light from the original are made the same optical system. When dust or dirt adheres to an optical component, the illumination light is irregularly reflected by the dust or dust and directly enters the lens or the image sensor as flare light, resulting in deterioration of the quality of the read image. .

  The object of the present invention is to detect foreign matter such as dust adhering to an optical component such as a mirror even when the illumination light and the reading light have the same optical system as in the prior art. An object of the present invention is to provide an image reading apparatus capable of reading quality and an image forming apparatus equipped with the image reading apparatus.

  In order to achieve the object, the invention described in claim 1 includes a lens that divides a light beam emitted from the light source into a plurality of light beams, and deflects and reads the plurality of light beams divided by the lens by a mirror. An image reading apparatus that illuminates the reading object by superimposing on the object, and causes the reflected light from the reading object to enter the image sensor through the mirror to read image information of the reading object, The light reflected by the foreign matter on the mirror is detected by the image sensor to detect the presence or absence of the foreign matter. With this configuration, if there is a foreign matter such as dust on the mirror, it can be detected. Therefore, it is possible to prevent reading of abnormal images.

  According to a second aspect of the present invention, in the image reading apparatus according to the first aspect, a flare detection member having a uniform concentration is provided at a portion other than the setting portion of the reading object, and the flare detection member is read to obtain flare light. The presence or absence of foreign matter is detected by detecting the flare, and foreign matter detection is reliably performed by detecting flare light with a uniform density flare detection member as a reference.

  According to a third aspect of the present invention, in the image reading apparatus according to the second aspect, the light irradiation surface of the flare detection member is black.

  According to a fourth aspect of the present invention, in the image reading apparatus according to the second or third aspect, the reflectance of the flare detection member is set to 30% to 70%.

  According to a fifth aspect of the present invention, in the image reading apparatus according to the second aspect, a flare detection member is formed by applying a black color or a paint having a reflectance of 30% to 70% to the inside of the apparatus housing. .

  According to a sixth aspect of the present invention, in the image reading device according to the second or third aspect, the flare detection member is formed by applying black flocking on the surface.

  According to a seventh aspect of the present invention, in the image reading apparatus according to the second or fourth aspect, a flare detection member is formed by projecting a large number of sharp protrusions on the surface.

  According to an eighth aspect of the present invention, in the image reading apparatus according to the first aspect, a flare detection mirror surface is provided in a portion other than the setting portion of the reading object, and the flare detection mirror surface is read to obtain flare light. It is characterized by detecting the presence or absence of a foreign substance by detection.

  According to a ninth aspect of the present invention, in the image reading device according to the first aspect, an opening is provided in a portion other than the setting portion of the reading object, the flare light is detected by reading the opening as the object. It is characterized by detecting the presence or absence of a foreign substance.

  According to a tenth aspect of the present invention, in the image reading device according to any one of the first to ninth aspects, the scanning body on which the mirror is mounted is moved from the image information reading position to the flare detection position, so that there is no foreign matter. The detection is performed.

  According to an eleventh aspect of the present invention, there is provided an image forming apparatus comprising: an image reading unit that reads a document image; and an image forming unit that forms an image on a recording medium based on image information obtained by the image reading unit. The image reading device according to any one of claims 1 to 10 is mounted as the image reading unit.

  According to the present invention, it is possible to detect the presence or absence of dust on the mirror by detecting the light reflected by the foreign matter on the mirror, which is an optical component on the optical path, by detecting the presence or absence of the foreign matter. Therefore, it is possible to prevent abnormal images from being read based on the detection information, and high-quality image formation can be performed.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of a copying machine which is an electrophotographic image forming apparatus for explaining an embodiment of the present invention. Around a photoconductor 21 in the apparatus main body, a charging charger 22, an exposure unit 23, and toner development. A unit 24, a transfer charger 25, and a photosensitive member cleaning unit 26 are provided.

  Further, an upper part of the apparatus main body is provided with a contact glass 1 on which a document is placed, and an image reading unit 28 for reading a document image on the contact glass 1, and an image optically read by the image reading unit 28. The photosensitive member 21 is exposed based on the information. In addition, a sheet storage cassette 29 on which sheets are stacked is provided at the lower part of the apparatus main body.

  A sheet as a recording medium is fed from the sheet storage cassette 29 by a pickup roller 30 and conveyed to a transfer charger 25 by a registration roller 31 in synchronization with the position of the toner image developed on the photosensitive member 21. Is done. The sheet on which the toner image has been transferred by the transfer charger 25 is sent to the fixing unit 32, and is subjected to heat and pressure to fix the image. Then, the sheet is discharged to the discharge tray 34 by the discharge roller 33.

  FIG. 2 is a schematic configuration diagram showing a basic configuration of the image reading unit in the present embodiment, and members corresponding to those described in FIGS. 8 and 9 are denoted by the same reference numerals and detailed description thereof is omitted.

  In FIG. 2, an image pickup unit 35 and an illumination device 36 are integrated in the image forming unit 28, and the basic configuration of the image pickup device 35 is the same as that described with reference to FIG. It consists of a one-dimensional image sensor 10. As will be described later, the basic configuration of the illumination device 36 includes an integrated lens 37, an illumination lens 38, a condensing lens 39, a light source 40, a rotary paraboloid mirror 41, and the like arranged with the same optical axis. Yes.

3A is a plan view showing the basic configuration of the illumination device, FIG. 3B is a front view of the illumination device of FIG. 3A, and an LED (light emitting diode) 42 as a light source 40 is linearly arranged. The ones arranged are used. Each LED 42 is sealed with a transparent resin and has a lens portion formed at the tip, and is formed so as to output a light beam emitted from the LED 42 as substantially parallel light. The condensing lens 39 is a lens that divides the light beam from the light source 40 in the main scanning direction and collects the light to transmit the entire light beam to the illumination lens 38, and has a cylinder shape as shown in FIG. A lens array in which cylinder lenses are arranged as shown in FIG. 4B, and cylinder lenses as shown in FIGS. 4C and 4D can be arranged. . The focal length f ₁ of each cylinder lens is at the distance c in FIG. 3 (ie, f ₁ = c).

Illumination lens 38 is a lens for illuminating the illumination target surface of the document D in a main scanning direction, is composed of a cylindrical lens array in the same manner as the condenser lens 39, the focal length f ₂ of each cylinder lens 3 In this case, it is possible to design (f ₁ = f ₂ ) that is approximately f ₂ = 1 / (1 / (a + b) + 1 / c). By doing so, the illumination lens 38 and the condenser lens 39 can be used as a member of the same standard).

The integrated lens 37 is a lens for superimposing the light beam divided and irradiated by the illumination lens 38 and the condenser lens 39 on the illumination target surface of the document D, and is a normal lens with the optical axis being axially symmetric. By setting the focal length to f ₀ = a, the optical axis (referred to as the secondary optical axis) of the light beam divided by the illumination lens 38 and the condenser lens 39 can be aligned with the center (main optical axis) of the illumination target surface. The divided light flux can be superimposed on the illumination target surface. In FIG. 3A, the illustration is omitted so as to show the light beam every other cylinder in the cylinder array in order to avoid the complexity of the drawing.

When the magnification of the image is described by the illumination lens 38, the focal lengths f ₂ and f ₀ of the illumination lens 38 and the integrated lens 37 are originally synthesized, but the description is simple because f ₂ << f _0. In order to achieve this, it is assumed that b = ₀ and ignoring f0 of the integrated lens 37.

Here, if the width of each cylinder lens of the condenser lens 39 which is a cylinder lens array is m ₁ and the irradiation width (main scanning direction) of the irradiation target surface of the document D is m ₀ , m ₀ / m ₁ = a / c (actually, f ₀ and f ₁ are determined after determining this relationship). With this setting, an image of size m ₁ of each cylinder of the condensing lens 39 is projected on the illumination target surface to a size of m ₀ , and all the light beams that have passed through m ₁ reach the illumination target surface. Normally, the illuminance unevenness is large in the illumination with the individual light fluxes from the respective cylinder lenses, but the illuminance becomes flat as a result of superimposing the whole as in this example.

  FIG. 4E is a perspective view showing the appearance of the rotary parabolic mirror 41, and an elliptical mirror can also be adopted.

Next, illumination in the illumination device in a direction perpendicular to the main scanning direction (sub-scanning direction) will be described with reference to FIG. The light beam emitted from the LED 42 encapsulated with the transparent resin in the light source 40 is output as a substantially parallel light beam by the lens portion at the tip. The condensing lens 39 and the illumination lens 38 have the same effect as a parallel plate when viewed from the plane side, so that the light beam that has become substantially parallel first passes through as parallel light with almost no influence. Since the focal length f ₀ of the integrated lens 37 is f ₀ = a, the light beam passes through the integrated lens 37 and is condensed on the illumination target surface of the document D.

  An image reading apparatus equipped with the illumination device 36 having the configuration shown in FIG. 3 is shown in FIG. 2, and the configuration of the imaging device 35 and the illumination device 36 in the image reading device is shown in the plan view of FIG. In FIG. 5, the deflecting mirror 6 and the folding mirrors 8a and 8b in the optical path shown in FIG. 2 are omitted.

  In FIG. 5, illumination devices 36 are arranged on both sides of the imaging device 35, and the integrated lens 37 is used as a lens with the portions removed from the center of the lens facing the illumination device 36. By doing in this way, the illuminating device 36 including the light source 40, the condensing lens 39, the illuminating lens 38, and the integrated lens 37 can be integrated as a unit and installed on both sides of the imaging lens 9, that is, the imaging device 35.

  As shown in FIG. 2, in this image reading apparatus, the optical axis viewed in the sub-scanning direction matches the reading optical axis of the imaging device 35 and the illumination optical axis of the illumination device 36. The reflecting surfaces of the folding mirrors 8a and 8b are shared for illumination and reading. Since these mirrors 6, 8 a and 8 b are installed with their mirror surfaces facing upward, there is a high possibility that dust G will adhere to the mirror surface, and once the dust G has adhered, the illumination light is diffusely reflected by the dust G, The flare light F directly enters the imaging lens 9 and is read by being superimposed on the image light of the document D on the one-dimensional image sensor 10, so that the image obtained by the one-dimensional image sensor 10 is read. A so-called black floating phenomenon occurs that causes whiteness.

  That is, when the illumination light is reflected on the mirror surface as described above, in general, most of the light is regularly reflected and a small amount of remaining light is absorbed. However, if dust G adheres to the light, Diffuse reflection occurs, and reflected light is scattered in all directions. As described above, when dust or dirt adheres to the deflecting mirror 6 or the folding mirrors 8a and 8b and illumination light is applied thereto, scattered light is generated in addition to reflection in the direction of the illumination target surface of the document D. The light returns parallel to the direction opposite to the direction from the illumination device, and flare light F is generated when a part of the light enters the imaging lens 9. This phenomenon tends to become more prominent as the mirror is closer to the lens (because it is closer to the illuminating device, strong scattered light becomes flare).

  Therefore, in this embodiment, the flare light F is detected so that an abnormal image can be prevented in advance. The specific configuration will be described in Embodiments 1 and 2 of the image reading apparatus according to the present invention shown in FIGS.

  In Embodiment 1 shown in FIG. 6, a flare detection reference plate 43 whose lower surface (light irradiation surface) is painted black is disposed outside the contact glass 1 on which the document is placed (outside the document reading area). When the flare detection operation is started, the first scanning body 5 moves to a position where the lower surface of the flare detection reference plate 43 is read, and the surface image is read by the one-dimensional image sensor 10.

  When there is no dust or dirt on the deflecting mirror 6 or the folding mirrors 8a and 8b, the entire read image becomes black, so that it can be determined that there is no foreign matter. However, when there is a foreign matter G such as dust on the deflecting mirror 6 or the folding mirrors 8a and 8b, scattered light is generated, and gray or white data is read into the read image in the one-dimensional image pickup device 10, and further the imaging lens. If there is dust on the mirror close to 9, whiter data is captured. Therefore, by comparing this data value with a preset threshold value and recognizing that flare light caused by the foreign object G is detected when the value is whiter than the threshold value, it can be determined that there is a foreign object. This recognition / determination operation is performed by arithmetic processing such as a CPU (Central Processing Unit) (not shown) mounted on the apparatus.

  Further, the flare detection reference plate 43 may have a lower surface coated with a paint having a reflectivity of 30% to 70%. When there is no dust or dirt on the mirrors 8a and 8b, it is recognized that the read image is gray on the entire surface and there is no abnormality. In addition, when there is dust or dirt on the deflecting mirror 6 or the folding mirrors 8a and 8b, data that is whiter than the other parts is read in the read image, and there is dust on the mirror close to the imaging lens 9. If it is, whiter data is captured. Then, in the same manner as described above, the presence of foreign matter is determined by comparing the data value with a preset threshold value and recognizing that flare light caused by the foreign matter is detected when it is whiter than the threshold value. Is called.

  In this way, by setting the reflectance of the flare detection reference plate 43 to 30% to 70%, it is possible to read changes in the image data more sensitively to a slight amount of flare light than the entire surface black, The detection ability can be increased.

  As in Embodiment 2 shown in FIG. 7, the opening 44, the transmissive glass, or the flare detection mirror is disposed outside the contact glass 1 on which the document is placed, and the first travel is performed when the flare detection operation starts. The body 5 is moved to a position where the open portion 44 or the transmission glass or mirror can be read as a reading target, and the image at the position is read by the one-dimensional imaging device 10 to detect foreign matter similar to the above. be able to.

  In addition, as the flare detection reference plate 43, one having flocked on the lower surface (preferably black hair) or one having a long and narrow sharp protrusion (preferably a black protrusion) disposed on the entire lower surface is adopted. can do.

  It is also conceivable to install the one corresponding to the flare detection reference plate 43 of each configuration inside the apparatus housing.

  The present invention is applied to a reading unit of various scanners such as a reduction optical system mounted on a digital copying machine or the like and equipped with a solid-state imaging device, an imaging lens, and an illumination device, or a film scanner and a book document scanner. In particular, the present invention is effective when applied to a configuration in which the optical systems of the illumination light and the reading light are the same.

1 is a schematic configuration diagram of a copying machine which is an electrophotographic image forming apparatus for explaining an embodiment of the present invention. Schematic configuration diagram showing a basic configuration of the image reading unit in the present embodiment (A) is a top view which shows the basic composition of the illuminating device of FIG. 2, (b) is a front view of the illuminating device of (a). (A)-(e) is a perspective view which shows the optical component in this embodiment. The top view which shows the structure of the imaging device and illuminating device in the image reading apparatus of this embodiment. 1 is a front view showing a main part of Embodiment 1 of an image reading apparatus according to the present invention. The front view which shows the principal part of Embodiment 2 of the image reading apparatus which concerns on this invention. The perspective view which shows schematic structure of the whole conventional image reading apparatus. Front view showing a main part of a conventional image reading apparatus

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Contact glass 5 1st traveling body 6 Deflection mirror 7 2nd traveling body 8a, 8b Folding mirror 9 Imaging lens 10 One-dimensional image sensor 21 Photosensitive body 28 Image reading part 35 Imaging device 36 Illumination device 37 Integrated lens 38 Illumination lens 39 Condensing lens 40 Light source 41 Rotating parabolic mirror 42 LED (light emitting diode)
43 Flare detection reference plate 44 Opening part

Claims (11)

A lens that divides the light beam emitted from the light source into a plurality of light beams; the plurality of light beams divided by the lens are deflected by a mirror and superimposed on the read object to illuminate the read object; An image reading apparatus that reads reflected image information of the reading object by causing reflected light from the object to enter the imaging device through the mirror,
An image reading apparatus, wherein the image sensor detects light reflected by foreign matter on the mirror to detect the presence or absence of foreign matter.   A flare detection member having a uniform concentration is provided in a portion other than the setting portion of the reading object, and the presence or absence of the foreign matter is detected by reading the flare detection member and detecting flare light. Item 2. The image reading apparatus according to Item 1.   3. The image reading apparatus according to claim 2, wherein the light irradiation surface of the flare detection member is black.   4. The image reading apparatus according to claim 2, wherein a reflectance of the flare detection member is set to 30% to 70%.   3. The image reading apparatus according to claim 2, wherein the flare detection member is formed by applying a paint having a black color or a reflectance of 30% to 70% to the inside of the apparatus housing.   4. The image reading apparatus according to claim 2, wherein the flare detection member is formed by applying black flocking on a surface thereof.   5. The image reading apparatus according to claim 2, wherein a plurality of sharp protrusions are provided on the surface to form the flare detection member.   The flare detection mirror surface is provided in a part other than the installation portion of the reading object, and the presence or absence of the foreign matter is detected by reading the flare detection mirror surface and detecting flare light. The image reading apparatus according to 1.   2. The presence or absence of the foreign matter is detected by providing an opening in a portion other than the setting portion of the reading object, reading the opening as an object, and detecting flare light. Image reading device.   The image reading apparatus according to claim 1, wherein the presence or absence of the foreign matter is detected by moving a scanning body on which the mirror is mounted from an image information reading position to a flare detection position. An image forming apparatus comprising: an image reading unit that reads a document image; and an image forming unit that forms an image on a recording medium based on image information obtained by the image reading unit.
An image forming apparatus comprising the image reading apparatus according to claim 1 as the image reading unit.

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